Agreed completely. If we can make a livable colony on Mars, surely we can make a livable colony on Earth even after the full effects of climate change have occurred.
The major threat of climate change is not to things so expansive as atmospheric viability, but only to present geography and weather cycles. There will still be breathable oxygen in the atmosphere, there will still be water, animals, and vegetation on the surface. As dystopic as a post-climate-change world may look, it undoubtedly looks better than Mars.
This is probably even true after massive nuclear winters, etc. I don't think there's anything humans can do that would so disadvantage Earth as to make another planet in our solar system better suited to human life. The only thing that may require external planetary colonization would be an extinction-scale geological or astronomical event (i.e., something totally outside of human control).
Considering that past CO2 levels have been well past 1500 ppm rather than the ~450 ppm at the moment, and considering that it is, after all, fossilized carbon that we are digging up and we are putting that carbon - you know the building block of life - back into the atmospheric carbon cycle where it bloody well came from, there is no reason to think some future Earth will be dystopic at all. It will if anything be more bountiful and teeming with life. More water vapour + more carbon = more life.
Here's a thought, C3 plant life goes extinct if CO2 falls below ~200ppm. No more rice, no more wheat, no more potatoes, no more evergreen trees. Life on earth would probably suffer a good deal more in the long run (in geological terms) if we left all fossilized carbon in the ground.
Sure, the rise of CO2 in the atmosphere is fine for life in general, but I don't really have a huge emotional attachment to the shallow-sea fish that will have all that lovely extra living space right where Miami used to be. The future Earth will not be dystopic for biodiversity, but it will make things more difficult for us, and that is, ultimately, what I care the most about.
I get that argument. Sure, it may be bad for certain ecosystems we currently rely on, or for the current configuration of human civilization. But the article we're discussing mentions the next 4 galactic orbits. No one will give a toss about Miami in 100 million years. I will be surprised if it is relevant in 10,000.
Do you have any convincing arguments for why a wetter, warmer, carbon-rich world would be a downside for humans on that scale? If I were betting on us surviving, I'd take that over an ice-age any day of the week.
Land, and especially coast, which is a lot of the areas most suitable for human habitation. Earth's surface is already 70% water; the ideal is probably 50%, so we should be looking to lower the water level rather than raise it.
Parasites and diseases, much more common in warmer, wetter places. You'll notice that on the whole tropical civilizations have been less successful than those in colder climes; there's a wide variety of possible reasons for that, but the effects of parasite load on health and general intelligence are real. Our technology/economy/etc. has so far been much better at helping us live in inhospitable cold places (Norway) than at dealing with tropical parasites and diseases.
Not to mention that a climatic shift on this timescale, in either direction, has historically meant about 20% of extant species going extinct. How lucky do you feel?
"It will if anything be more bountiful and teeming with life."
In the near term, it's going to cause tremendous dislocation of human civilizations. In poorer areas, climate change will cause millions to die and tens of millions to suffer. That's the undeniable moral component.
Ecologically, climate change will hasten the mass extinction of species. A world covered in kudzo, algae, and roaches is technically "teeming with life", but I'm not sure it's the aesthetic vision you have in mind.
The major threat of climate change is not to things so expansive as atmospheric viability, but only to present geography and weather cycles. There will still be breathable oxygen in the atmosphere, there will still be water, animals, and vegetation on the surface. As dystopic as a post-climate-change world may look, it undoubtedly looks better than Mars.
This is probably even true after massive nuclear winters, etc. I don't think there's anything humans can do that would so disadvantage Earth as to make another planet in our solar system better suited to human life. The only thing that may require external planetary colonization would be an extinction-scale geological or astronomical event (i.e., something totally outside of human control).